The present invention is generally directed to ink jet printers. More particularly, the invention is directed to an ink jet print head integrated circuit chip that supports two different drive schemes to provide two different levels of performance at two different printer costs.
Ink jet printers form images on a print medium by ejecting droplets of ink from nozzles in a print head as the print head translates across the print medium. The nozzles are generally arranged in one or more columns that are aligned orthogonal to the direction of translation of the print head. Ink is ejected from a selected nozzle when an ink-heating resistor associated with the selected nozzle is activated based on print control signals.
Generally, in a three-dimensional nozzle addressing scheme, nozzle selection is based upon a combination of three sets of control signals. These control signals are typically carried from printer controller electronics to contacts on the print head by way of a flexible wiring harness. These signals are carried from the print head contacts to the print head integrated circuit chip by way of a tape automated bonding (TAB) circuit, with each control signal in the three sets of signals being carried by a separate metal conductor in the TAB circuit. These metal conductors in the TAB circuit and the corresponding conductors in the flexible wiring harness represent a significant portion of the total cost of an ink jet printer.
In the past, print head integrated circuit designs have supported a single print head drive scheme which provided a single print resolution and print speed as determined by the layout of the integrated circuit chip. This limits the usefulness of the chip design to a narrow performance range.
Since conventional print head integrated circuit chip designs have been limited to a single drive scheme, the number of control lines that connect the chip to the printer electronics have also been limited to a particular number. Thus, achieving a different printer cost by changing the number of control lines has in the past required a completely different print head chip design.
Therefore, a single print head integrated circuit chip that supports more than one cost/performance design point is needed.
The foregoing and other needs are met by an ink jet print head which is controllable based at least in part on q number of first control signals and p number of second control signals. The print head includes a print head integrated circuit chip having ink-heating resistors for generating heat when activated. The print head chip also has a switching circuit for receiving the first and second control signals, and for selectively activating the ink-heating resistors by allowing electrical current to flow through selected ink-heating resistors based at least in part on the first and second control signals. The switching circuit is operable in either a first operating mode or a second operating mode, where q is equivalent to q1 in the first operating mode, and is equivalent to q2 in the second operating mode, and where q1 is greater than q2. In a most preferred embodiment, q1 is twice q2. In the first operating mode, p is equivalent to p1, and in the second operating mode, p is equivalent to p2, where p2 is greater than p1. Most preferably p2 is twice p1. In the most preferred embodiment, the product of q1 multiplied by p1 in the first operating mode is equivalent to the product of q2 multiplied by p2 in the second operating mode. The print head also includes an operating mode selection circuit connected to the print head integrated circuit. The operating mode selection circuit determines, based on a configuration of the operating mode selection circuit, whether the switching circuit operates in the first operating mode or the second operating mode.
In the first operating mode, the print head requires four passes across a print medium to completely print an image, while in the second operating mode, the print head requires only two passes. Thus, a print head implemented according to the second operating mode offers a higher performance design point. However, a print head implemented according to the first operating mode is less expensive to manufacture. Therefore, the invention provides a single print head integrated circuit chip which may be used for two different cost/performance design points, the selection of which depends upon the configuration of the operating mode selection circuit.